Material choice does not update render view
Answering my own question, because I happened upon it in another post:

How can I swap Textures and Materials

To change the active material assignment, I noticed a couple options:

Option 1:


Go into Edit mode for the object
Choose your desired material from the Materials list
Click on the "Assign" button to apply that material to your object


Option 2:


Go into Object or Edit mode for the object
Click the black down-arrow to the right of the Materials list, a menu opens below
Choose "Assign Material" -> {name of desired material} and it will apply that material to your object


Somehow in my "beginners" reading and tutorials, I missed this detail.  Leaving this answer here in case it's useful for others.